Interpretive Summary: Barley is one of the most salt tolerant crops, however, there are conflicting reports as to whether selection under non-saline conditions can be effective in identifying salt tolerant germplasm, or tolerance to salinity at the early stages of growth will be expressed at latter stages. Selection indices, based on germination, seedling growth, and forage yield at the tillering stage under increasing salinity levels, were instrumental in identifying accessions in the Batini barley landrace from Oman. These highly salt tolerant accessions fully germinated, survived and produced 1,590, 1,425 and 393 grams per meter squared forage yield in 6 weeks at no-salinity, 1/4 and 1/2 strength sea water salinity levels, respectively. This germplasm can be genetically improved to increase its yield potential under high salinity stress and would be of value to farmers in areas where saline water and soil resources are under utilized.

Technical Abstract:
Genetic diversity was assessed for germination and seedling growth in 2,308 accessions at 0.0 and 20.0 dSm**-1 salinity stress; and at 0.85, 10.0, and 20.0 dSm**-1 for forage yield potential at the tillering stage in 70 families representing seven subpopulations of the Batini barley landrace from Oman. Seedling attributes, especially temporal variation in, and thermal time to 50% germination, combined with differences among subpopulations in relative seedling dry weight under salinity stress, clearly identified highly salt tolerant subpopulations at the germination stage. A multivariate-based selection criterion for high forage yield at tillering stage was formulated and is based on simultaneous selection for low temporal variation in germination and a high shoot dry weight at 20.0 dSm**-1. Variance structure at the seedling and tillering stages were dominated by subpopulation components, thus indicating a strong genetic control over seed germination in barley, especially under high (20.0. dSm**-1) salinity stress. Positive phenotypic correlations, found between germination attributes under stress and non-stress conditions, can be exploited through phenotypic selection to improve germination under stress. Salt tolerance indices at the germination and seedling growth stages (low temporal variation, low thermal time to 50% germination and mg root mg seed dry weight**-1 at 20.0 dSm**-1) and at tillering stage (forage yield, g per 100 unit thermal time at 20.0 dSm**-1)were positively correlated. There were large differences among subpopulations, and significant interactions with salinity levels for forage yield at the end of tillering stage. On average, forage yield was reduced by 19.4 and 55.6 (2.4 and 7.9%, respectively) g m**-2 per dSm**-1 at 10.0, and 20.0 dSm**-1, respectively. We identified highly salt tolerant genotypes in the Batini landrace, with short rachilla hair that can fully germinate, survive and produce 45% more forage than the landrace average at 20.0 dSm**-1. Although genetically not improved, the germplasm can be used to increase salt tolerance in selection and breeding.